Magnet wire is manufactured by applying a coating of enamel to a filament of copper or aluminum conductor. Typically, the conductor is passed through a bath of liquid enamel or a solution of enamel in a solvent and then heated in an oven to drive off the solvent and to cure the enamel. Coating thickness is an important design parameter and it is very important to control the thickness of the coating within a predetermined range. The coating thickness is strongly dependent upon the viscosity of the liquid enamel or enamel solution and the viscosity of the enamel must be carefully controlled in order to provide a uniform coating thickness. Conventional methods of controlling the viscosity of the enamel coating have proven inadequate in that wide variation in enamel viscosity is permitted and wire coatings are allowed to vary out of the predetermined specification range. When the coating thickness drifts out of specification, the production line must be shut down, the problem corrected, and the defective product scrapped.
What is needed in this art is an apparatus for closely controlling the viscosity of wire coating enamel.